Coordinate switch



June 21, 1960 w. HATTON ETAL COORDINATE SWITCH 2 Sheets-Sheet 2 FiledSept. 6. 1955 MEMMRES' INVENTORS Y M Am N w A M0 #7 Y B COORDINATESWITCH William Hatton, South Orange, and George F. McCarthy, Teaneck,N.J., assignors to International Telephone and Telegraph Corporation,Nutley, N.J., a corporation of Maryland Filed Sept. 6, 1955, Ser. No.532,719

15 Claims. (Cl. 179--27.'54)

This invention relates to electrical switching systems and morepatricularly to a coordinate contact switch.

The coordinate or cross-bar switch heretofore commonly used in automatictelephone switching systems is a rather delicately adjusted instrumentrequiring numerous parts assembled in a compact arrangement. Thenumerous contacts and selective actuating mechanism must, afterassembly, be carefully adjusted for proper operation and since theswitch is compact, this calls for painstaking manipulation in order notto disturb other adjusted parts. Where a part becomes worn or otherwiseinoperative, the switch assembly usually requires a major disassemblingjob before the particular part canv be repaired or replaced.Furthermore, most contacts in such switches have a rubbing action whichlimits the life ofthe contacts and also produces objectionable dust onthe working parts, thus interfering with good contact operation.

One of the objects of this invention is to provide an improvedcoordinate contact switch which overcomes the above-mentioned and manyother disadvantages of prior coordinate switches. More particularly, theobjects of this invention include the following: a simplified andsturdier switching mechanism; a horizontal multiple contact panelarrangement to which terminals may be coupled'at both ends of the paneland which can be easily divided into separate switching groups, as maybe desired; a novel flexible active contact conductor strip; and aselective contact actuating arrangement including spring elements forselecting contact pusher members for actuation and mechanism foractuating a selected pusher member.

One of the important features of this invention is the panelconstruction containing passive contacts for the switch. The panelcomprises twocards or sheets of dielectric, one being provided withprinted horizontal multiple circuitry and the other with passive contactareas which are connected through to the printed circuitry.

Other features include the arrangement of the active contacts in theform of one or more flexible ribbon-like strips disposed in overlyingrelation to a row of the printed passive contacts, a pluralityofresilient pusher members corresponding in number tothe number of passivecontacts, disposed for movement relative thereto to engage the activeconductor strips and elfect electrical connection between the. stripsand the passive contacts. The ribbon-like strips are provided withU-shaped portions to permit flexing thereof when the strip is engaged bya pusher member, the strips being also slotted and provided with dimpledcontact portions which are flashed with nickel and coated with a layerof rhodium for making pressure contact with the passive contact. areaswhich may also be similarly coated with nickel and rhodium. Eachselective pusher member is arranged with a cushionlike pad adapted toengage a plurality of conductive strips for multiple contact actuation,the pad operating to insure satisfactory pressure contact for all of thecontact. strips and further, to transmit pressure to each of the 2strips substantially directly proportional to the pressure exerted uponthe pusher member. The member for actuating and holding the pushermembers include a simple helical spring which is exceptionally durableand positive in its selective operation.

The above-mentioned and other features and objects of this inventionwill become more apparent by reference to the following descriptiontaken in conjunction with the accompanying drawings, in which:

Fig. 1 is a fragmentary view in side elevation of one panel of acoordinate switch for use in an automatic telephone switching systemembodying the contact units of this invention;

Fig. 2 is a sectional view taken along line 22 of Fig. 1;

Fig. 3 is a view in plan of one section of the switch, the view beingtaken along line 3-3 of the central portion of Fig. 2;

Fig. 4 is an enlarged sectional view taken along line 4-4 of Fig. 3;

Fig. 5 is a cross-sectional view taken along line 5-5 of Fig. 4; and

Fig. 6 is an enlarged cross-sectional view of one of the ribbon stripsshown in Fig. 5.

While this invention is shown as a part of an automatic telephoneswitching system, it will be understood, however, that the invention isalso useful in other switching systems wherever selective switching isrequired.

Referring particularly to Figs. 1, 2, 4 and 5, it will be observed thatthe switch is provided with a passive contact panel 1 which includes abase frame member 2 and two layers or cards of insulating material 3 and4. Card 3 has thereon printed circuitry 5, Fig. 1, which constituteshorizontal multiples having terminals at each end of the panel asindicated at 6 and 7. The circuitry 5 may be formed on the card 3 by anyone of the many different printed circuit techniques, the circuitrybeing so arranged as to avoid the openings 8 through which selectivefingers 9 extend, and to provide groups of junctions 10. The card 4overlies the printed horizontal circuitry 5 and contains thereon ingroups passive contacts 11, 12, 13 and 14, each of which is connected bya junction tab 10a to a corresponding junction of circuitry 5. Each suchgroup of passive contacts is arranged in horizontal alignment andconstitutes with adjacent groups of passive contacts a vertical rowacross the panel 1. The flat contact surface of the passive contacts ispreferably flashed with nickel and plated with rhodium. While each groupof passive contacts is shown to comprise four contacts, it will berecognized by those skilled in the art that each group may be less thanfour or greater than four depending upon the circuitry associated witheach group.

From the foregoing description and reference to Figs. 1-5, it is clearthat the groups of passive contacts are arranged in ten vertical rowsand that each row has in overlying relation thereto a contact'unit 15.Each contact unit 15 comprises a housing having side walls 16 and 17,end walls 18 and 19 and a cover plate 20. The bottom side of the housingis open so that when placed on the panel 1, it encloses a vertical rowof passive contact groups. The open side, however, has bridge elementsas indicated at 21 and 22, Fig. 4, so arranged as to lie at leastbetween'certain groups, or as shown, between adjacent groups of passivecontacts. In overlying relation to each horizontal group of passivecontacts is a contact pusher member 23 guided by two ribs 24 and 25contained on the side walls 16 and 17, Fig. 4. The pusher membercomprises a semi-tubular frame 26 which has a stem 27 adapted to extendthrough an opening 28 in the vided with a resilient pad 29, of doubletubular stock Patented June 21, 1960 preferably of silicon rubber forengaging the ribbon contact strip.

While the pad 29 is shown of double tubular stock, other shapes or evena single tube may be used so long as it has a tubular or hollow portionexposed for unrestricted fiexing when subjected to compressive actionand thereby equalize the pressure of the pusher member onto a pluralityof associated ribbon contact strips. One of the advantages of thetubular pressure pad is that its resilient resistance to compression isdirectly proportional, i.e., a straight line function, within ratherwide limits as compared to the logarithmic pressure curve of a solidpad. The semi-tubular frame member 26 may also be of other shapesdepending upon the shape of the pad stock selected.

Each unit 15 is also provided with four ribbon contact strips 30, 31, 32and 33. Each strip is preformed by a stamping or other shape formingoperation and is mountedat its ends on the step portions 34 of the endwalls 18 and 19, the strip overlying the bridge elements such as 21 and22 and being slotted lengthwise thereof at least in the portions betweenadjacent bridge elements. Each strip is also provided with U-shapedportions 35 adjacent its ends which enhances the flexibleness of thestrip to permit movement of the strip by any one or more of the pushermembers. As shown in Fig. 2, the ends of the strips are provided withterminals 36 and 37 which are receivable in the sockets 38 and 39 on thepanel 1.

Referring to Fig. l, the panel 1 is normally chosen of a size such thatten. vertical rows of horizontal contact groups and ten units 15 ofactive contact strips are employed. Each contact unit 15 has ten pushermembers and each vertical row has ten groups of horizontal passivecontacts This provides for a possible selection of 100 difierentswitching connections between the. horizontallines represented by thehorizontal groups of pas.-

sive contacts and those lines represented by the ribbon Panels havingstill larger or a smaller number of switching connections are,v

strips of each of the contact units.

of course, contemplated. The horizontally disposed conductors which areconnected to the passive contacts may be connected from the panel toeach of the terminal blocks 6 and 7 or if desired they may be dividedbetween the two terminal blocks. In Fig. 1 such a division is indicatedat 40 simply by severing circuitry between the third and fourth units.In such a division, 30 switch.

connections are associated to terminal block 6 and. 70 switchconnections are associated with terminal block 7. Other ratios such as40-60 or 5050 etc., may be provided by suitably severing the circuitry5.

As previously mentioned the pusher members 23 are provided with stems 27which extend through openings 28 in the cover plate of. the contactunit. The fit between the stem and the opening is close so that there islittle chance of dust working into the contact unit by way of M theopenings 28. The stem 27 is provided with a shoulder 41 which is adaptedto be engaged by a selecting spring 42, Figs. 3 and 4. The spring 42 isanchored on a holding or vertical bar 43 as indicated at 44. While thespring 42 is preferably a simple helical coil to insure properresilience and durability, it may take any one of several differentforms so long as it is sufficiently resilient and yet provide thedesired interlocking operation between the stem of the pusher member 23and the vertical bar 43. As shown in Fig. 5, one end 42a is clampedbetween the two parts 43a and 43b while the other end 4212 is free forlimited movement in the slot 430, Fig. 4. The position of the selectingspring 45 represents the normal position of the selecting springs whilethe position of the spring 42 is that assumed upon actuation by aselecting finger 9. It will be understood by those skilled in the artthat the sequence of operation is first the movement of the selectingfinger 9 to move one or the other of the springs 42 or 45 to a selectingposition overlying the shoulder 41 on the associated pusher.

member. The next movement is that of the vertical bar 43 which pivotsdownwardly against the end 42b of the actuated spring 42, therebyforcing the pusher member 23 against the ribbon contacts. These' twomovements are caused by electromagnets, the selecting finger 9 beingconnected to a selecting horizontal bar 46 which in turn is connected toan armature 47 adapted to be attracted by one or the other of magnets 48and 49. The horizontal bar 46 is pivoted by journals 51 and 52. As shownin Fig. 2, the magnet 48 has attracted the armature 47, thereby causingthe selecting finger 9 to move to the right, Figs. 2 and 4, therebyactuating the spring42 to engage the shoulder 41 of pusher member 23.Should the magnet 49 attract the armature 47, the selector finger 9would then move to the left and engage the spring '45. in associationwith each of the horizontal bars 46 is a horizontal normal contact unit53 and a restoring spring 54 which are engaged by an arm 55 carried bythe bar 46. The vertical bar 43 is pivoted on the frame of the panel 1as indicated at journals 56 and 57, Figs. 1 and 2. Each of the bars 43is provided with an armature 58 which is associated with anelectromagnet 59 whereby the bar 43 is pivotally actuated in a clockwisedirection as viewed in Figs. 1 and 5 to actuate any pusher member thatmay be engaged by a selecting spring.

Each of the ribbon contact strips 30-33 is provided with longitudinalslots to render the strip more flexible and also to provide the stripwith a pair of relatively independent contact dimples in overlyingrelation to the adjacent passive contact. Two such dimple contacts areshown at 60 and 61 in Fig. 6. The strip isdivided between the two dimplecontacts by the slot 62. The slot adds independent resilience tothe'contact points. It is also preferred to have the U-shaped portion 35slotted as indicated at 63. The material for the ribbon strips ispreferably copper or brass clad at least on the-contact side with aflash of nickel60a and coated in thearea of the dimple contact with alayer of rhodium 60b. The

nickel flash found most suitable is .0007 inch minimum thick while therhodium layer was preferably 200 millionths of an inch thick. Theseproportions are preferred since the nickel provides a good base for therhodium and the latter does not thin down or otherwise migrate underrepeated pressure contact engagement; The passive contacts'llto 14 aswell as the dimpled portions of the strip are plated and coated withrhodium to insure durable pressure type contacts. If desired, thedimpling effect may be provided on the passive contacts 11-14 instead ofon the strips 30-33, although the latter is preferred.

To summarize the operation of the switchingactiom it may be assumed thatthe electromagnet 48 is energized for each of-the ribbon strips 30-33forcing the contactdimples 60 thereof into pressure engagement with theassociated group of passive contacts 11-14. The holding bar 43 remainsin a holding position until its associated magnet 49 is deenergizedwhereupon the bar rotates: counterclockwise to another position therebyreleasing:

spring 42 and pusher member 23 to return to their normal positions.position, the selecting finger 9 is left free to move for selectiveactuation of the spring 45. It should also be recognized that in aninstallation having more thanone" panel 1 that the finger 9 may beextended onthe other side. of thebar 46 for use in a second panel.

While we have described above the principlesof -our inventionin'connection with specific apparatus, .it is to While the vertical bar43 is in holding.

be clearly understood that this description is made. only by way ofexample and not as a limitation to the scope of our'invention as setforth in the objects thereof and in the accompanying claims.

We claim:

1. ha coordinate switch, a panel having a plurality of discrete flatpassive contacts spaced apart in a row, an elongated active fiatconductor disposed in overlying relation to said row of passivecontacts, pusher members corresponding in number to the number ofpassive contacts of said row, means disposing each of said pushermembers in overlying relation to said active conductor and in alignmentwith one of said passive contacts whereby movement of any of saidmembers against said active conductor forces said conductor intoengagement with the corresponding passive contact, over a correspondingwide area, a holding device disposed for movement rela tive said row ofpassive contacts, selector elements associated with said holding device,selecting means to selectively position said selector elements relativeto said pusher members to effect transfer of an actuating force fromsaid holding device to a selected one of said pusher members when saidholding device is actuated, and means for actuating said holding device.

2. A coordinate switch according to claim 1, wherein said activeconductor presents a first set of contact engaging surfaces, saidpassive contacts present a second set of contact engaging surfacesplated with rhodium, and one of said sets of contact surfaces comprisesdistinct dimples disposed toward the other of said sets of contactengaging surfaces.

3. A coordinate switch according to claim 1, wherein saidactive-conductor comprises a ribbon-like strip and each of the contactengaging portions of said strip is provided with distinct dimples,covered with rhodium for contact purposes.

4. A coordinate switch according to claim 1, wherein said activeconductor comprises a flat ribbon-like strip and said strip is providedwith means to enhance flexing thereof when said strip is engaged by oneof said pusher members.

5. A coordinate switch according to claim 4, wherein said strip isslotted lengthwise throughout the portions adapted to engage saidpassive contacts and the parts of the strips divided by the slot areeach provided with a contact dimple plated with a non-corroding metal.

. 6. A coordinate switch according to claim 4, wherein the means toenhance flexing of said strip includes a U-shaped bend in said stripdisposed transversely of the flat surface of said strip. 7

7. A coordinate switch according to claim 1-, wherein said panel hasassociated therewith a plurality of ridgelike elements one each disposedbetween adjacent passive contacts to limit contact engagement betweensaid active conductor and the particular passive contact associated withan actuated pusher member.-

8. A coordinate switch according to claim 1, wherein each of saidselector elements comprises a helical spring and said holding deviceincludes means to support one end of said helical spring whilepermitting the other end thereof to be moved by said selecting meansinto a pusher member engaging position. i i

,9. A coordinate switch according to claim 1, wherein each of saidselector elements comprises a helical spring and said holding devicecomprises a bar pivoted for movement about a longitudinal axis parallelto said row of passive contacts, said bar having means to anchor one endof each of said helical springs and leave the other end thereof free formovement by said selecting means into a pusher member engaging position.

, 10. A coordinate switch according to claim 1, comprising a pluralityof said rows of passive contacts which present a first set of contactengaging surfaces, a plurality of said active conductors correspondingin number to the number of said rows which present a second set ofcontact engaging surfaces, with all said contact eng'ag ing surfaces ofsaid first set lying in a first plane, and

with all of said contact engaging surfaces of said second saidcontactsbeing arranged in groups with the'cohtac'ts of each group spacedapart in a horizontal row and said groups being arranged in a row at anangle to said horizontal row, flat, ribbon-like active conductorsdisposed as parallel bands of contacts in overlying relation tocorresponding ones of the passive contacts of said groups, pushermembers corresponding in number to the number of said groups, meansdisposing each of said pusher members in overlying relation to saidactive conductors and in alignment with the passive contacts of one ofsaid groups whereby movement of any of said members against said activeconductors forces said conductors into engagement with the passivecontacts of the corresponding group, a holding device disposed formovement relative of passive contacts of all said groups, selectorelements associated with said holding device, means to selectivelyposition said selector elements relative to said pusher members toeffect transfer of an actuating force from said holding device to aselected one of said pusher members, and means for actuating saidholding device.

12. A coordinate switch according to claim 11, comprising a plurality ofsaid rows of groups, wherein said passive contacts present a first setof contact engaging surfaces, said active conductors present a secondset of contact engaging surfaces, all of said contact engaging surfacesof said first set lie in a first plane, and all of said contact engagingsurfaces of said second set which are in the normal position lie in asecond plane in spaced relation parallel to said first plane.

13. In a coordinate switch, a panel having a printed board with aplurality of passive contacts arranged in a given plane, said passivecontacts being arranged in groups with a number of such groups arrangedin a row, the contacts of each group being spaced apart in a rowtransversely of the row of said groups, a plurality of flat stripsadapted to be flexed and forming moveable, active conductors disposed incontiguous relation, spacing means supporting said active conductors inspaced parallel relation to correspond with the spaced relation of thepassive contacts in each of said groups, pusher members corresponding innumber to the number of said groups, means to locate each pusher memberin crosswise relation to said active conductors and in alignment withthe passive contacts of one of said groups and to guide said pushermember for movement against said active conductors to thereby flex saidactive conductors into contact engagement with the passive contacts ofsaid one group, selecting means to select one of said pusher members,and means to actuate the selected pusher member to effect a selectedswitching opera-tion between said active conductors and said passivecontacts.

14. A coordinate switch according to claim 11, wherein, each of saidflat strips is slotted lengthwise thereof and the two parts of thestrips divided by the slot are each provided with a contact projection.

15. In a coordinate switch, an insulating panel with a printed boardhaving a plurality of fiat passive contacts arranged in rows in a givenplane, a plurality of flat, thin, flexible active conductors one eachbeing disposed in overlying relation to a row of said passive contacts,a pair of terminal blocks, each of said blocks having terminalscorresponding in number to the number of passive conother of said rowsto corresponding terminals of theother of said blocks, and a pivotedcontacted pusher for 7 8 flexing and for selectively pressing saidactive conductors 2,117,702 Burwell May 17, 1938 to client contactclosure between a selected active con- 2,300,371 Malinna Oct. 27, 1942tact and a selected passive contact. 2,447,010 Harrison Aug. 17, 19482,516,772 Hickman July 25, 1 950 References Cited in the file of thispatent 5 2,735, 95 01 7,1, 195

UNITED STATES PATENTS 2,066,491 Sheatsley I an. 5, 1937

